Dust cap assembly for sealing an optical fiber ferrule and methods thereof

ABSTRACT

A dust cap assembly includes a sleeve and a sealant that seals an end face portion of a fiber optic ferrule from contaminants and, upon removal, provides remedial cleaning of any foreign matter present on the ferrule when the dust cap assembly was initially installed along with methods of making the same. The sleeve of the dust cap assembly has a through bore and a distal end for receiving the sealant. Further, the sealant may optionally have advantageous mechanical and optical properties such that the dust cap assembly may function as a terminator for testing.

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional ApplicationSerial Nos. 61/182,379 and 61/182,361 both filed on May 29, 2009, theentire contents of both which are incorporated herein by reference.

BACKGROUND

1. Technical Field

The disclosure relates to dust cap assemblies for fiber optic ferulesused in fiber optic connectors. Specifically, the dust cap assemblyseals the fiber optic ferrule from contaminants during its incumbencyand, upon removal, provides remedial cleaning of any foreign matterpresent on the ferrule when the dust cap assembly was initiallyinstalled. In other embodiments, the dust cap assembly may optionallyfunction as a terminator for testing the integrity of an optical cableassembly or as enabling a non-contact continuity test for fiber opticpatch cables.

2. Technical Background

The capacity to send information over a wire revolutionizedcommunication. Copper wire was the standard for more than 150 years,with ease of use and interconnection, but as bandwidth demand increased,it was necessary to seek alternative mediums. Optical fiber, developedand perfected over the past three decades, has made its presence felt,providing secure, high capacity signal transmission; in the past usedprimarily for long distance signal transmission due to its tremendousefficiency and security, but unable to easily leverage these attributesin more localized arenas. With developments in the joining of truncatedfibers, suddenly optical fiber was becoming as versatile as copper.Optical fiber could be cut and easily rejoined via splicing, either bylaser, electric arc or mechanical splicing, and by other mechanicalprocesses. Of the mechanical processes developed, the ability to mateand de-mate an optical fiber to another optical fiber completed theversatility picture. Fiber optic ferrules and fiber optic connectorsprovided easy junction points in the field that tremendously increasedthe ease of use of optical fibers. Polishing optical fibers withinappropriate ferrules is necessary to efficiently join two fibers end toend in such a way as to preserve the integrity of the optical signalwith as little signal loss (attenuation) as possible.

To create a typical fiber optic cable assembly a fiber optic cable isterminated, a fiber optic connector is assembled at an end of the cableand the ferrule end face polished. The exactitude of the polished faceof a fiber optic ferrule is such that any minute amounts of debris onthat end face can block or decrease signal transmission or even damagethe end face. Polished ferrule end faces can represent the end result ofhours of manufacturing providing a polished ferrule end face to mate toanother polished ferrule end face and thereby transfer signals from onefiber into another. Protecting the polished end faces of fiber opticferrules is extremely important: protection from residual dust from theconnector housing; protection from airborn contaminants in themanufacturing facility; protection from the effects of water, oils andchemicals; protection from the effects of temperature cycling, just toname a few. Dust caps as known in the art provide a shield from thephysical contact of the delicate ferrule end faces with the outsideenvironment, but do not inherently preventingress of moisture, remediateexisting contaminants, and can actually deposit contaminants onto thevery ferrule end faces they are designed to protect. Thus, there is anunresolved need for dust cap assemblies that will literally seal theoptical ferrule end face, insuring the integrity of the factory polishedferrule, one that is inexpensive, easy to install and remove, and thatprevents contamination by water, oil, dust, particulates, damage due tohandling, etc.

SUMMARY

The disclosure refers generally to a dust cap assembly for a fiber opticconnector and methods for making the same. Specifically, the dust capassembly physically engages and seals a polished fiber optic ferrule,thereby preserving the cleanliness of the fiber optic ferrule end face.The dust cap assembly comprises at least two components: a sleeve and asealant. The sleeve has a through bore that physically engages the fiberoptic ferrule by a frictional fit. A distal end of the sleeve mayinclude an encapsulating feature that provides a suitable applicationpoint for the sealant. The distal end is proximal to the fiber opticferrule end face, thereby allowing application of the sealant to theencapsulating feature of the sleeve and the fiber optic ferrule end faceat the same time.

In one embodiment, the sealant comprises a curable liquid polymer,wherein the curable liquid polymer is easily applied and generallyconforms to the geometry present on the distal end of the sleeve and thefiber optic ferrule end face. The sealant transitions from liquid tosolid upon curing, encapsulating the fiber optic ferrule end face andprotecting it from contaminants such as water, oils, dust, particulates,etc., thereby ensuring the integrity of the polished fiber optic ferruleend face.

In the event that contaminants are present prior to the application ofthe sealant, the sealant will adhere to such contaminants and lock themin the polymer upon curing. The contaminants, locked in the curedsealant, will come away with the dust cap assembly when the craftremoves it from the fiber optic ferrule, leaving a fiber optic ferruleend face surface that may be cleaner than before the dust cap assemblywas installed.

A further optional advantage of the present disclosure is theinteraction of the dust cap assembly and optical testing equipment usedby the craft. In one embodiment, the index of refraction of the curedsealant allows the dust cap assembly to act as a terminator so that thecraft can remotely test the optical integrity of an optical system afterthe system has been installed. If the dust cap assembly is installed oneach end of a cable, as in a fiber optic jumper, the encapsulatingconvex shape of the index matching sealant serves as a lens, allowinglight to enter from an external light source sufficient to travel thelength of the cable and exit the opposite dust cap assembly and bedetected by a photodetector. This helps the craft to quickly determinecontinuity within the jumper without having to remove the dust capassembly or optically connect the jumper cable to either the externallight source or the testing apparatus. Removing the dust cap andplugging the ferrule into testing equipment runs the risk of damaging orcontaminating the polished fiber optic ferrule end face.

The present disclosure provides assurance to the end user that thefactory installed, polished fiber optic ferrules remain pristine and inexcellent condition for and until their intended use—transmission ofoptical signals from one optical fiber into another optical fiber.

It is to be understood that both the foregoing general description andthe following detailed description present embodiments of the invention,and are intended to provide an overview or framework for understandingthe nature and character of the invention as it is claimed. Theaccompanying drawings are included to provide a further understanding ofthe invention, and are incorporated into and constitute a part of thisspecification. The drawings illustrate various embodiments of theinvention, and together with the description serve to explain theprinciples and operation of the invention.

BRIEF DESCRIPTION OF THE FIGURES

Embodiments of the disclosure are illustrated by the accompanyingdrawings, in which:

FIGS. 1A and 1B show two views of an embodiment of the sleeve of a dustcap assembly;

FIGS. 2A and 2B show two views of another embodiment of a sleeve havinga shoulder;

FIG. 3A shows a sectional view of a fiber optic connector with thesleeve installed and FIG. 3B shows a sectional view of the same fiberoptic connector and sleeve with the sealant in place;

FIG. 4A shows a sectional view of a fiber optic connector with anothersleeve installed and FIG. 4B shows a sectional view of the same fiberoptic connector connector and sleeve with the sealant in place;

FIG. 5A shows a sectional view of a fiber optic connector with anothersleeve installed and FIG. 5B shows a sectional view of the same fiberoptic connector and sleeve with the sealant in place;

FIG. 6A shows a sectional view of a fiber optic connector with anothersleeve installed and FIG. 6B shows a sectional view of the same fiberoptic connector and sleeve with the sealant in place;

FIG. 7 shows a multi-fiber fiber optic ferrule assembly with the dustcap assembly installed;

FIG. 8 depicts a first method of sealing a fiber optic ferrule end faceusing a dispensing head to deposit the sealant and then curing the same;

FIG. 9 is a second method of sealing a fiber optic ferrule end face bydipping the sleeve and polished end face into the sealant and thencuring the same;

FIG. 10A shows an artistic rendering of a “clean” polished end facebefore application of the dust cap assembly and FIG. 10B shows anartistic rendering of the polished end face of FIG. 10A after the dustcap assembly was removed;

FIG. 11A shows an artistic rendering of a “dirty” polished end facebefore application of the dust cap assembly and FIG. 11B shows anartistic rendering of the polished end face of FIG. 10B after the dustcap assembly was removed

FIG. 12 schematically shows a jumper cable assembly with the dust capassembly on each end during continuity testing;

FIG. 13 schematically shows a jumper cable assembly with a firstconnector optically connected to a test apparatus and a second connectorhaving a dust cap assembly during testing for backreflection; and

FIG. 14 shows a fiber optic cable assembly with a trunk cable andtether, the tether having a dust cap assembly acting as a terminator.

DETAILED DESCRIPTION

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings, in which some, but not all embodiments of the invention areshown. Indeed, the invention may be embodied in many different forms andshould not be construed as limited to the embodiments set forth herein;rather, these embodiments are provided so that this disclosure willsatisfy applicable legal requirements. Whenever possible, like referencenumbers will be used to refer to like components or parts.

The disclosure generally relates to a dust cap assembly and methods ofmaking the same. The dust cap assembly comprises at least two componentsfor sealing a polished end face of a fiber optic ferrule of a fiberoptic ferrule assembly. Sealing a polished end face of a fiber opticferrule is advantageous to inhibit encroachment of contaminants on thepolished end face from the time the polished end face is polished to thetime the fiber optic connector assembly is deployed in the field. Simplystated, the disclosure is directed to a dust cap assembly for sealing afiber optic connector assembly having at least one fiber optic ferruleassembly including a fiber optic ferrule having at least one opticalfiber therein. The sleeve has a proximal end and a distal end with athrough bore therebetween and is disposed on the at least one fiberoptic ferrule, and a sealant at least partially disposed on the sleevefor sealing a portion of the polished end face of the fiber opticferrule.

FIGS. 1A and 1B show two different views of a sleeve 10 of the dust capassembly of the disclosure. In this embodiment, the sleeve 10 isgenerally straight and has a proximal end 14 and a distal end 16. Theproximal end 14 and distal end 16 have a through bore 12 therebetween,creating a generally hollow component. An encapsulating feature 18proximal to the distal end 16 is in communication with the through bore12, wherein the encapsulating feature 18 enables the sealing of thepolished end face of a fiber optic ferrule. FIGS. 2A and 2B show twodifferent views of a second embodiment of a sleeve 20. Sleeve 20includes a shoulder 22 for easing the removal of the same from the fiberoptic ferrule assembly (e.g., the assembly includes a portion of thefiber optic ferrule and the end of the optical fiber). Sleeve 20 alsohas distal end 16 and proximal end 14 with a through bore 12therebetween. Encapsulating feature 18 is proximal to distal end 16 andin communication with through bore 12.

FIGS. 3A-B through FIGS. 6A-B show two different sectional views ofrespective dust cap assemblies 30 disposed on a fiber optic connector 32(hereinafter “connector”). FIGS. 3A, 4A, 5A and 6A show connector 32having a ferrule 28 with a single fiber 26 and respective embodiments ofsleeve 20. Ferrules include, but are not limited to, LC, SC and MT,utilizing APC, UPC, pencil tips or flat configurations, made of steel,ceramic, polymer or any other suitable ferrule material. Each ferrule 28has an exposed polished end face 27, the polished end face 27 havingpolished fiber face 27A protruding slightly, but the fiber face 27A maybe flush or recessed. For purposes of this disclosure polished end face27 and polished end face 27A are proximal to each other and any furthermention of polished end face 27 is meant to include by inferencepolished fiber face 27A. However, the concepts of the presentapplication may be used on ferrule assemblies that are not polished,where protection is desired. FIG. 3A shows sleeve 20 having anencapsulating feature 18 shaped as a chamfer 24 that extends from thethrough bore 12 to distal end 16. In a similar fashion, FIGS. 4A, 5A and6A show respective embodiments of dust cap assembly 30, each havingsleeve 20 with different configurations of encapsulating feature 18. InFIG. 4A encapsulating feature 18 is shaped as a radius 40. In FIG. 5A,encapsulating feature 18 is shaped as a step 42 and in FIG. 6Aencapsulating feature 18 is shaped as a lip 44. Of course, othersuitable geometries are possible as the encapsulating feature. Each ofrespective FIGS. 3B, 4B, 5B and 6B show sealant 34 generally coveringrespective portions of the through bore 12 and encapsulating feature 18.Sealant 34 is advantageous for sealing the polished end face 27 and isin direct contact with polished end face 27 as well as portions ofencapsulating feature 18.

FIG. 7 shows a multi-fiber ferrule assembly 50 having a dust capassembly employing the concepts disclosed herein. In other words, thedust cap assembly includes a sleeve 48 and sealant 34 for sealing aplurality of polished fiber faces and a portion of polished end face 37of the multi-fiber ferrule 46. Multi-fiber ferrule sleeve 48 isgenerally rectangular, having proximal end 14 and distal end 16 thatgenerally surrounds the end of multi-fiber ferrule assembly 50 as shown.Specifically, sleeve 48 surrounds a portion of multi-fiber ferrulepolished end face 37 of multi-fiber ferrule 46. Multi-fiber ferrulesleeve 48 has a through bore 49 and encapsulating feature 24 shaped as achamfer, but other geometries are possible. Sealant 34 is in directcontact with chamfer 24 and multi-fiber ferrule polished end face 37,thereby sealing and protecting the multi-fiber ferrule polished end face37. Multi-fiber ferrule assemblies 50 may include guide pins 47 disposedtherein for mating with a complementary ferrule assembly. As shown,guide pins 47 are received and protected from encroachment of sealant 34by guide pin cavities 49A and 49B formed in sleeve 48. The multi-fiberferrule sleeve 48 shown in FIG. 7 may have other variations similar tosleeves 10 and 20 of FIGS. 1-6 such as alternative encapsulatingfeatures for receiving the sealant 34 for sealing multi-fiber ferrulepolished end face 37. Other embodiments of the multi-fiber sleeve mayhave other geometries such as including one or more protrusions forfitting into the guide pin bores of the ferrule if it does not includeguide pins.

Sleeves 10, 20 and 48 of the disclosure may use any suitable materialand the bores frictionally engage their respective ferrules, slightlydeforming to tightly slide along a medial portion of the respectiveferrule. This prevents sealant 34 from wicking down the medial portionof the ferrule, keeping sealant 34 on polished end face 27. By way ofexample, the sleeve may be a polymer such as a thermoplastic likepolycarbonate and a polyacrylate, though other suitable thermoplasticsmay be used.

Sealant 34 may be any suitable material having the desired propertiesfor sealing and/or optical transmission. In one embodiment, sealant 34is a curable liquid polymer. The curable liquid polymer starts as aliquid having a viscosity range of generally less than 1000 poise at 23degrees Celsius, with a preferred range of about 250 poise to about 850poise at 23 degrees Celsius. This range provides advantageous physicalcharacteristics, e.g., ease of handling, tackiness, and surface tensionqualities. For instance, sealant 34 of FIGS. 3-7 shows a generallyconvex shape 38 distal from the sealed polished end face 27, enabled bythe surface tension of sealant 34 while in liquid state; however, othershapes for the sealant such as generally flat are possible. Upon curing,sealant 34 retains its geometry and hardens, enabling sealant 34 tofully integrate with respective sleeves 10, 20 or 48. Encapsulatingfeature 18 is configured in such a way that when dust cap assembly 30 isremoved sealant 34 releases sealed polished end face 27, revealingpolished end face 27. The sealant 34 viscosity range allows sealant 34to flow sufficiently to fully cover polished end face 27 andencapsulating feature 18.

The curable liquid polymer may be a heat curable liquid polymer, anultraviolet light curable liquid polymer or a chemically reactive liquidpolymer. One preferred embodiment of sealant 34 is an ultraviolet lightcurable liquid polymer for providing the speed and ease of processing.By way of example, one suitable ultraviolet light curable liquid polymeris a UV acrylate that consists essentially of an aliphatic urethanediacrylate, a difunctional acrylate oligomer, and a photoinitiator. Therange of ratios of each ingredient are:

-   -   100 parts aliphatic urethane diacrylate;    -   0-40 parts difunctional acrylate oligomer; and    -   2-6 parts photoinitiator,        with a preferred ratio being 100 parts aliphatic urethane        diacrylate, 10 parts difunctional acrylate oligomer and 3 parts        photoinitiator. This ratio of ingredients provides appropriate        sealing, viscosity and optical qualities, enabling sealing,        cleaning and testing advantages for dust cap assembly 30.

Additionally, sealant 34 is preferably a hydrophobic polymer, resistingwater absorption that can contaminate sealed polished end faces 27.Water ingress can leave deposits on polished end face 27, degradingtransmission quality of mated fiber optic connectors. Keeping water andoils away from polished end face 27 effectively insures thatcontaminants are also prevented from contacting polished end face 27.

FIGS. 8 and 9 illustrate two different methods for making the dust capassemblies disclosed herein. Generally speaking, the methods of sealinga fiber optic ferrule end face includes the steps of: providing a fiberoptic connector assembly having at least one fiber optic ferruleassembly therein that includes at least one fiber optic ferrule and atleast one optical fiber therein, wherein the fiber optic ferrule has apolished end face thereon; providing a sleeve having a proximal end anda distal end with a through bore therebetween; placing the sleeve ontothe fiber optic ferrule via the through bore, whereby the polished endface is proximal to the distal end of the sleeve; and depositing asealant onto the sleeve to cover a portion of the polished end face ofthe fiber optic ferrule and a portion of the distal end of the sleevefor sealing the fiber optic ferrule end face.

Sleeve 10 is placed onto the ferrule and frictionally engages a medialportion of a ferrule within a fiber optic connector assembly 51. Thesleeve 10 is slid onto the ferrule a suitable distance so that thedistal end 16 is proximal to polished end face 27. Encapsulating feature18 exposes polished end face 27, thereby providing a suitable catchmentarea for the sealant 34 (see FIGS. 3-7). In other words, the distal end16 may extend beyond the polished end face or be substantially flushwith the polished end face 27. Additionally, polished end face 27 mayextend slightly beyond distal end 16, but polished end face 27 should beproximal to distal end 16. Sealant 34 is applied by any suitableapplication means in sufficient quantity to cover both the polished endface 27 and at least a portion of the distal end 16. If there is anencapsulating feature 18 associated with the distal end 16, the sealant34 should cover the polished end face 27 and the encapsulating feature18.

FIG. 8 specifically illustrates a method of sealing a fiber opticferrule end face where a plurality of fiber optic ferrule end faces ofrespective fiber optic connector assemblies 51 are sealed. As shown,fiber optic connector assemblies 51 having sleeves 10 installed aresecured to a common connector holder 52 at regular intervals.Thereafter, dispensing head 60 with a plurality of nozzles matching theregular intervals is brought adjacent to the distal end 16 of therespective sleeves. A controlled amount of sealant 34 within dispensinghead 60 is deposited out by mechanical, pneumatic, and/or electricalmeans onto the respective distal ends 16, covering a portion of distalends 16 and polished end faces 27 of respective fiber optic connectorassemblies 51. Then, connector holder 52 is moved to a curing station asrepresented by the arrow. In this embodiment, an ultraviolet lightcurable polymer sealant is used and an ultraviolet light source 54 forcuring the same. A suitable dose and exposure time is selected forultraviolet light 55, thereby providing the desired cure as shown.

FIG. 9 illustrates another explanatory method of sealing a fiber opticferrule end face where a plurality of fiber optic ferrule end faces ofrespective fiber optic connector assemblies 51 are sealed. Like theother method, the plurality of fiber optic connector assemblies 51having respective sleeves 10 are secured to connector holder 52. Theplurality of fiber optic connector assemblies 51 are inverted and thedistal ends 16 of sleeves 10 are brought into contact with the surfaceof sealant 34, allowing a small quantity of sealant 34 contained withina suitable container to adhere to the distal end 16 and polished endface 27. The viscose properties of the sealant 34 will promote evencoating on the surfaces. Thereafter, connector holder 52 is reverteduntil the dust cap assembles 30 point vertically upwards and then movedinto proximity of an ultraviolet light source, or other curing means asappropriate. Thereafter, the dust cap assemblies 30 are exposed to asuitable amount of ultraviolet light 55 for curing the sealant. Althoughthe methods discussed disclosed making a plurality of dust capassemblies at once, the concepts are applicable to making individualdust cap assemblies.

Referring to FIGS. 10A-B and 11A-B, one can see the results of sealingpolished end face 27 of a ferrule assembly through artistic renderingsof actual test samples. FIG. 10A shows an artistic rendering of actualclean, newly polished end face 27 and polished fiber face 26. FIG. 10Bshows an artistic rendering of actual polished end face 27 of FIG. 10Aafter dust cap assembly 30 was installed and removed. As shown, thepolished end faces 27 in both illustrations are clean. In other words,the end face was clean at the time of manufacture and sealing, andretained its clean state when the dust cap assembly was removed.

FIG. 11A shows an artistic rendering of actual polished end face that iscontaminated at the time of manufacture such as by dust and the like.Dust cap assembly 30 was installed and FIG. 11B shows artistic renderingof the results after dust cap assembly 30 was removed. The same polishedend face 27 of FIG. 11A is very clean in FIG. 11B after removing thedust cap assembly. Simply stated, dust cap assembly 30, utilizingsealant 34, is able to remedially clean polished end faces 27. This isadvantageous due to the environmental conditions within a processingfacility; dust, pollen, particulate matter, moisture, oils, lint, etc.,are usually floating in the air and can stick to polished end face 27.Dust cap assembly 30 protects polished end face 27 while residing on theferrule, and further, upon removal, cleans any incidental contaminantspresent on polished end face 27 at the time of the installation of dustcap assembly 30.

Additionally, the dust cap assembly 30 can provide other optionalfunctionality. For instance, sealant 34 such as disclosed herein canhave advantageous post-cure optical properties. The pre-cure viscosityrange allows the sealant to create a convex shape 38 about the sealedpolished end face 27. By way of example, the convex shape 38 may have atangential contact angle of greater than about 5 degrees and less thanabout 90 degrees, preferably about 10 degrees. Additionally, theformulation of the sealant may provide a post-cure index of refraction(RI) within the range of between about 1.45 to about 1.48 at 23 degreesCelsius and at a wavelength of 589 nm, most preferably between about1.460 and about 1.466 at 23 degrees Celsius. At 1310 nm wavelength RI ofthe cured sealant at 23 degrees Celsius should be about 1.45. This rangeof RI closely matches most commercial optical fiber and allows theoptical signal to travel into the sealant. This RI range also helps thedust cap assembly to withstand very high power levels, as high as 23 dBmfor testing as discussed below.

Simply stated, the convex shape 38 of the sealant coupled with thepreferred RI of the cured sealant 34, allows light to enter the dust capassembly with great efficiency since there is no gap between the sealant34 and polished end face 27 and then escape from the sealant.Illustratively, FIG. 12 shows a jumper cable assembly 85 with dust capassemblies 30 installed on both ends. An external light source 80 isproximal to a first dust cap assembly 30 and a photoreceptor 81 isproximal to a second dust cap assembly 30. Emitted light 57 from theexternal light source 80 (represented by the arrows) enters the firstdust cap assembly 30 and travels along the jumper cable assembly 85 andthen exits the second dust cap assembly 30 where it is detected byphotoreceptor 81. This enables a continuity test for jumper cableassembly 85. Photoreceptor 81 is useful to determine the amount ofactual light transmitted, regardless of wavelength. If external lightsource 80 is a visible light source the photoreceptor 81 may be simplythe human eye (not shown). The continuity test advantageously does notrequire removal of dust cap assemblies 30, thereby maintaining apristine end face until the dust cap assemblies are removed forinstallation of the jumper cable assembly 85.

Other improvements in testing are possible with assemblies using thedust cap assemblies disclosed herein. FIGS. 13 and 14 use the geometricand optical qualities of dust cap assembly 30 for improving areflectance test. The reflectance test is useful since it can reveal alot of useful information to the craft such as the integrity of a cableassembly. An unterminated distal connector (e.g., not connected toanother connector, other device, or other means to inhibitbackreflection) without the dust cap assembly disclosed herein can be asource of a large backreflection spike. This large spike in reflectedsignal is detrimental to the quality of light emitting devices such asVCSELs that rely on amplified internal reflections to boost theirsignal. Backreflected light entering such a light emitting device cancause noise or utterly disrupt the signal.

In the past discrete terminators needed to be installed as conventionaldust caps did not have the inherent utility of a terminator. Placing anindex matching gel, or index matching block was one way to terminate acable assembly. Mandrel wrapping the cable multiple times to a radiusbeyond the minimum bend radius of the particular optical fiber wasanother, causing the light signal to reflect out of the cladding wallinstead of being reflected from the end. However, this mandrel wrappingmethod is not effective with new bend-insensitive optical fibers thatdirect light along their specialized core almost regardless of bendradius. Thus, another type of terminator is necessary in such cases.Dust cap assembly 30 optionally provides a ready made terminator alongwith the functionality of sealing, protecting and cleaning the polishedend face 27.

Terminating the distal fiber optic connector assembly 71 eliminates thespike in backreflection, causing the light from the light source or testapparatus 83 to pass out of the dust cap assembly 30 as shown in FIG.13. Specifically, the convex shape 38 of the sealant prevents most lightfrom reflecting back into the optical fiber, and by consequence, back tothe light source or test apparatus 83. FIG. 13 shows a first fiber opticconnector assembly 70 of jumper cable assembly 85 optically connected totest apparatus 83. A second fiber optic connector assembly 71 is notoptically connected to any device, but has dust cap assembly 30installed. Test apparatus 83, such as an OTDR or the like, sends a pulseof light into jumper cable assembly and takes minute amounts ofbackreflection and determines the integrity of the fiber optic cableassembly. The dust cap assembly 30 serves as a terminator to prevent thelarge spike in backreflection commonly associated with light passingfrom a polished fiber face into air. The amount of backreflectionallowed by the dust cap assembly 30 is not more than −50 dB, and in mostcases as little as −60 dB. FIG. 14 shows a cable assembly having a fiberoptic trunk cable 90 and a cable access point 91 with a fiber optictether cable 86 issuing from the cable access point 91. The distal endof the fiber optic tether cable 86 has fiber optic connector assembly71, with dust cap assembly 30 installed. Light from a remote upstreamsource such as a central office (not shown) or the like can be sent fromthe fiber optic trunk cable 90, into the fiber optic tether cable 86 andto the fiber optic connector assembly 71, to pass out of the dust capassembly 30, again greatly reducing the backreflection spike commonlyfound at the polished fiber face/air interface.

The foregoing is a description of various embodiments of the disclosurethat are given here by way of example only. Although a dust cap assemblyfor sealing a fiber optic ferrule according to the disclosure has beendescribed with reference to preferred embodiments and examples thereof,other embodiments and examples may perform similar functions and/orachieve similar results. All such equivalent embodiments and examplesare within the spirit and scope of the present invention and areintended to be covered by the appended claims.

1. A dust cap assembly for sealing a fiber optic connector assemblycomprising: at least one fiber optic ferrule assembly including a fiberoptic ferrule having at least one optical fiber therein, wherein thefiber optic ferrule assembly has a polished end face; a sleeve, having aproximal end and a distal end with a through bore therebetween, thesleeve being disposed on the at least one fiber optic ferrule; and asealant at least partially disposed on the sleeve for sealing a portionof the polished end face of the fiber optic ferrule.
 2. The assembly ofclaim 1, wherein the sleeve frictionally engages a portion of the fiberoptic ferrule.
 3. The assembly of claim 1, wherein the at least onefiber optic ferrule is a multi-fiber fiber optic ferrule.
 4. Theassembly of claim 1, wherein the sleeve frictionally engages a portionof the multi-fiber fiber optic ferrule.
 5. The assembly of claim 1,wherein the sealant is a curable liquid polymer selected from the groupconsisting of a heat curable liquid polymer, an ultraviolet lightcurable liquid polymer and a chemically reactive liquid polymer.
 6. Theassembly of claim 1, wherein the curable liquid polymer has a pre-cureviscosity range of about 1000 poise or less at 23 degrees Celsius. 7.The assembly of claim 5, wherein the curable liquid polymer has apre-cure viscosity range of about 250 poise to about 850 poise at 23degrees Celsius.
 8. The assembly of claim 5, wherein the curable liquidpolymer has a post-cure index of refraction between about 1.45 to about1.48 at 23 degrees Celsius.
 9. The assembly of claim 5, wherein thecurable liquid polymer has a post-cure index of refraction between about1.460 to about 1.466 at 23 degrees Celsius.
 10. The assembly of claim 1,wherein the sealant is a hydrophobic polymer.
 11. The assembly of claim1, wherein the sealant is an ultraviolet light curable hydrophobicpolymer consisting essentially of an aliphatic urethane diacrylate, adifunctional acrylate oligomer, and a photoinitiator.
 12. The assemblyof claim 1, the sleeve having a distal end and a proximal end with athrough bore therebetween, wherein the through bore is in communicationwith at least one encapsulating feature on at least the distal end. 13.The assembly of claim 12, wherein the encapsulating feature consists ofa chamfer, a lip, a step and a radius.
 14. The assembly of claim 1,wherein at least a portion of the sealant generally forms a convexshape.
 15. The assembly of claim 14, wherein the convex shape has atangential contact angle of greater than about 5 degrees but less thanabout 90 degrees.
 16. The assembly of claim 1, the dust cap assemblyproviding remedial cleaning of the polished end face upon removal of thedust cap assembly.
 17. The assembly of claim 1, wherein the sleeve iscomprised of a thermoplastic.
 18. The assembly of claim 17, thethermoplastic being selected from the group consisting of apolycarbonate, a polyolefin, a polyamide and a polyacrylate.
 19. Amethod of sealing a fiber optic ferrule end face, comprising the stepsof: providing a fiber optic connector assembly having at least one fiberoptic ferrule assembly therein, the at least one fiber optic ferruleassembly having at least one fiber optic ferrule and at least oneoptical fiber therein, wherein the fiber optic ferrule has a polishedend face thereon; providing a sleeve, the sleeve having a proximal endand a distal end with a through bore therebetween; placing the sleeveonto the fiber optic ferrule via the through bore, whereby the polishedend face is proximal to the distal end; depositing a sealant onto thesleeve to cover a portion of the polished end face of the fiber opticferrule and a portion of the distal end of the sleeve for sealing thefiber optic ferrule end face.
 20. The method of claim 19, wherein the atleast one fiber optic ferrule is a multi-fiber fiber optic ferrule. 21.The method of claim 19, the step of depositing a sealant forming aconvex shape.